Some new results on the Turán number of star forests

作者：

Highlights：

• Determine ex(n,Sℓ1∪Sℓ2) for ℓ2≥3,ℓ1≥2ℓ2+2 and n≥2ℓ1+2ℓ2. Thus, the value ex(n,Sℓ1∪Sℓ2) for ℓ1≥ℓ2≥2ℓ2+2 and n≥2ℓ1+2ℓ2 are determined completely.

• Determine ex(n,Sℓ1∪Sℓ2∪Sℓ3) for ℓ1≥ℓ2≥2ℓ3+1 and n≥max{M1,M2}, where both M1 and M2 are two parameters only depending on ℓ1,ℓ2andℓ3.

• Improve the corresponding two results due to Lidický et al. (2013).

摘要

•Determine ex(n,Sℓ1∪Sℓ2) for ℓ2≥3,ℓ1≥2ℓ2+2 and n≥2ℓ1+2ℓ2. Thus, the value ex(n,Sℓ1∪Sℓ2) for ℓ1≥ℓ2≥2ℓ2+2 and n≥2ℓ1+2ℓ2 are determined completely.•Determine ex(n,Sℓ1∪Sℓ2∪Sℓ3) for ℓ1≥ℓ2≥2ℓ3+1 and n≥max{M1,M2}, where both M1 and M2 are two parameters only depending on ℓ1,ℓ2andℓ3.•Improve the corresponding two results due to Lidický et al. (2013).

论文关键词：Star,turán number,Sℓ1∪Sℓ2∪Sℓ3

论文评审过程：Received 5 January 2021, Revised 15 April 2021, Accepted 25 April 2021, Available online 10 May 2021, Version of Record 10 May 2021.

论文官网地址：https://doi.org/10.1016/j.amc.2021.126320